Bluetooth: mt7921s: support bluetooth reset mechanism

Implement .cmd_timeout to reset the MT7921s device via a dedicated GPIO
pin when the firmware hang or the command has no response.

Co-developed-by: Mark Chen <mark-yw.chen@mediatek.com>
Signed-off-by: Mark Chen <mark-yw.chen@mediatek.com>
Co-developed-by: Sean Wang <sean.wang@mediatek.com>
Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Signed-off-by: Chih-Ying Chiang <chih-yin.chiang@mediatek.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>